Firing mechanism for cannons



y 1968 H. J. REEPMEYER 3,390,609

FIRING MECHANISM FOR CANNONS Filed Aug. 23. 1966 3 Sheets-Sheet 1 BEN-INVENTOR Hermun .l'Regpmgye'r ATTO-RNEY July 2, 1968 H. J. REEPMEYER3,390,609

FIRING MECHANISM FOR CANNONS Filed Aug. 23. 1966 3 Sheets-Sheet 2 Eig .3

36 Fig E| INVENTOR Harman l Regpmgyar ATTOIRNEY July 2, 1968 H. J.REEPMEYER 3,390,609

FIRING MECHANISM FOR CANNONS Filed Aug. 23. 1966 3 Sheets-Sheet 5INVENTOR Herman lReepmgrer ATTORNEY United States Patent 3,390,609FIRING MECHANISM FOR CANNONS Herman J. Reepmeyer, Cohoes, N.Y., assignorto the United States of America as represented by the Secretary of theArmy Filed Aug. 23, 1966, Ser. No. 574,874 2 Claims. (Cl. 89-27)ABSTRACT OF THE DISCLOSURE In a firing mechanism for cannons the firingpin is cocked and released by a straight pull on the lanyard with thesear located in a transverse shaft for rotational displacement therewithto cock the firing pin and translational displacement therein to releasethe firing pin. The end of the sear is cammingly contactable with a wallon the firing pin for converting rotational displacement of the searwith the shaft to translational retraction of the firing pin and thesear is so located respective to the wall that the angular relationshipof the design axis of movement of the sear in the shaft to the wallincreases as the firing pin is retracted so that a portion of the forceapplied by the sear to the wall is transmitted back to the sear fortranslational displacement to a position out of engagement with the wallfor release of the firing pin.

This invention relates to cannons and pertains more particularly to thefiring mechanisms thereof.

It has been the growing trend for the firing mechanisms of cannons to beautomatically cocked and fired responsive to movement of the cannon asactuated by recoil forces. Trouble, however, is being experienced withsuch firing mechanisms inthat the firing pin is sometimes releasedbefore the breechblock is fully closed and locked. With those cannonswhich fire cartridge rounds this is not too serious as the percussionelement in the cartridges is of rather small diameter so that thebreechblock must be almost completely closed and locked in order for thefiring pin to align with the percussion element.

In cannons, however, such as howitzers which use bagtype percussionelements having relatively large sensitive areas the firing pin cancause detonation before the breechblock is safely closed and locked.Consequently, it has been desirable for the firing mechanisms in suchcannons to be manually actuated so that firing can be better controlled.

It is therefore one object of this invention to provide for cannons amanually actuated firing mechanism which is distinguished for itssimplicity of operation and construction and which requires a minimum ofmachining in the breechblock for installation therein.

It is another object of this invention to provide such a firingmechanism which is easily and quickly replaced.

It is a further object of this invention to provide such a firingmechanism in which the firing pin is cocked and released by a continuouspull on a lanyard and which includes means for adjusting the position ofattachment of the lanyard to the firing mechanism so that the firingmechanism can be actuated by direct pull of the lanyard from allquadrant elevations of the cannon.

It is still another object of this invention to provide such a firingmechanism in which the sear is displaceable both angularly andtranslationally by pull on the lanyard to reduce the amount ofdisplacement required thereof to fire the cannon.

The specific nature of the invention as well as other objects andadvantages thereof will clearly appear from a description of a preferredembodiment as shown in the accompanying drawings in which:

3,399,509 Patented July 2, 1968 "ice FIG. 1 is an elevational view ofthe breechblock of a cannon;

FIG. 2 is an enlarged view taken along line 22 of FIG. 1;

FIG. 3 is an enlarged view taken along line 3-3 of FIG. 2 and shows thefiring mechanism with all the members in their static positions;

FIG. 4 is a view similar to FIG. 3 but showing the firing pin partiallyretracted by angular displacement of the sear and the sear partiallydisplaced translationally to its release position;

FIG. 5 is a view similar to FIGS. 3 and 4 but showing the acceleratingmember released from the sear and the striking member impelled forwardlyby its inertia to the firing position;

FIG. 6 is an enlarged view taken along line 66 of FIG. 2; and

FIG. 7 is a perspective View of the extending end of the actuatingdevice shaft and the adjustable ring mounted thereon.

Shown in the figures is a cannon 12 such as the mm. Howitzer XM138 whichis provided with a laterally displaceable breechblock 14. Formed inbreechblock 14 is a longitudinal bore 16 and a transverse bore 13 formounting a firing mechanism 20. The axis of bore 18 transversesbreechblock 14 below that of bore 16 and such bores are arranged tointersect to form a communicating mouth 21 therebetween, as shown inFIG. 2.

Bore i6 is of stepped configuration and includes a rear section 22 whichextends forwardly from the rear face of breechblock 14 to an annularshoulder 24, a second section 26 of smaller diameter which extends fromshoulder 24 to another shoulder 28, a third section 30 of still smallerdiameter which extends from shoulder 28 to a shoulder 32, and a frontsection 34 leading from the third section to the front face of thebreechblock.

Bore 16 houses a firing pin assembly 36 for discharge of a barrelchambered round and includes an accelerating member 38 and an inertialstriking member 40. Accelerating member 38 is received by rear section22 for sliding displacement between a retracted .position and a forwardposition wherein the front end of the accelerating member is in contactwith shoulder 24. A spring 42 is disposed between a rearwardly facingshoulder 44 on accelerating member 38 and a retainer 46, arranged toreleasably block the rear end of bore 16, whereby the acceleratingmember is biased to its forward position. An annular channel 48 isformed in accelerating member 38 forwardly of a circumferential area 50.Channel 48 is of rectangular configuration in cross section and includesa rear wall 51 which is normal to the axis of accelerating member 38.

Striking member 48 is slidingly received by second section 26 fordisplacement between a retracted position and a firing position whereina forwardly facing shoulder 52 on the striking member is in contact withshoulder 2-8 in bore 16. A spring 54 is disposed between shoulder 52 onstriking member 49 and shoulder 32 of bore 16 for biasing the strikingmember to its retracted position, Striking member 40 includes aforwardly extending pin 58 which is arranged to project from the frontface of breechblock 14 for firing a chambered round when the strikingmember is in its firing position.

Striking member 40 also includes an axial shank 60 which extendsrearwardly so as to be slidingly received by a mating hole 62 in thefront end of accelerating member 38. A pin 64 extends transverselythrough the front end of accelerating member 38 so as to pass throughhole 62 and a longitudinally elongated slot 66 through shank 60 to joinstriking member 40 to accelerating member 38 yet permit limited relativemovement therebetween. Shank is terminated by an end 68 which iscontactable by a. bottom wall 69 of hole 62 for transferring forwarddisplacement of accelerating member 38 to striking member 40.

Bore 18 mounts an actuating device 70 for manually actuating firing pinassembly 36. Actuating device 70 includes a shaft 72 rotatinglyjournaled in core l8 and such shaft carries a sear 74 of bladeconfiguration which is slidingly mounted in an accommodating ilOt 76 forradial displacement relative to the shaft between an outer engagingposition and an inner release position along a design axis of movement,noted at .t.t' in FIG. 4. A spring 78 biases sear 74 to its engagingposition and the displacement of the sear is limited through thecooperation of a pin 80 through shaft 72 with an elongated slot 82 inthe sear.

When in its engaging position, sear 74 extends from shaft 72 throughmouth 21 for engagement with channel 48 so that rotation of shaft 72 ina direction to press an extending end 84 of the sear against rear wall51 of the channel actuates accelerating member 38 into its retractedposition. Extending end 84 of seal 74 inclines outwardly and rearwardlyfrom the front face thereof and a radius 86 is formed where the outerface of the sear oins the rear face thereof.

A section 88 at one end of shaft 72 pro ects from breechblock 14 througha collar 90 which 18 tixed as by bolt means to the respective sidethereof. A pin 92 extends from section 88 into a radial opening 94 incollar 90 and such opening is formed as noted in FIG. b. so as tocooperate with the pin in preventing axial displacement of shaft 72while permitting sutficient rotation thereof for angular displacement ofsear 74 from .1 normal position, wherein extending end 84 of the sear isreceived by channel 48 when accelerating member .38 is in its forwardposition, to a disengaged position wherein the extending end iswithdrawn from the channel when the accelerating member is displacedthereby to its retracted position.

Rotatingly mounted on the end or section 88 is a ring 96 having aradially projecting ear 98 with an orifice for attachment of a lanyard100. Ring 96 is adiustably engaged =with shaft 72 by engagement of theextending ends of a rod 102 mounted through section 88 with a selectedpair of a plurality of angularly related grooves llt34 formed in theoutside face of the ring, as shown in FIG.

A torsion-compression spring 196 is mounted over section 88 betweencollar 90 and ring 96 with one end anchored to the ring and the oppositeend anchored to the collar. Thus, ring 96 is pressed by spring 106outwardly, respective to breechblock 14, to firmly engage rod 102 with aselected pair of the grooves 104 and thereby engage the ring to shaft72. When the angular position of ring 96 respective to shaft 72 needs tobe changed so that the shaft may be rotated by a direct pull on lanyardN0, the ring is pressed inwardly until the engaged grooves ill-4 arefree of rod 102 and then the ring is free to be rotated to the desiredposition. Release of ring '96 permits engagement of rod 102 with thenearest pair of grooves 104 through the bias of spring 106. With theopposite ends of spring 106 anchored to collar 90 and ring 96 and rod102 engaged with a pair of the grooves 164, the torsion of the spring istransferred from the ring to the shaft which is thereby biased angularlyto locate sear 74 in its normal position, as shown in FIG. 2.

Referring to FIGS, 3-5, it is seen that when sear 74 is displacedangularly by shaft 72 from its normal to its disengaged position, radius86 contacts rear wall 51 and axis of movement xx of the sear in theshaft is so angularly related to the end wall, as seen in FIG. 4. thatthe pressure of the radius against the end wall. by the pull on thelanyard against the tension of spring 42, causes the sear to betranslationally displaced inwardly to its release position. Thus, theangular displacement of shaft 72 required to disengage sear 74 fromtiring pin assembly 4 i6 is less than that which would be required ifthe sear was not also radially displaceable in the shaft.

Operation When breechblock 14 is closed and cannon 12 is ready to betired, actuating mechanism 70, as shown in FIG. 3, is biased by spring106 so that sear '74 is located in its normal position and is extendedby spring 78 to its engaging position respective to channel 48;accelerating member 38 is biased by spring 42 to its forward position;and striking member 40 is biased by spring 54 to its retracted position.

When cannon 12 is to be fired, lanyard is pulled, causing shaft 72 to berotated whereupon extending end 84 of sear 74 contacts rear wall 51 toretract accelerating member .38 rearwardly from its forward position.lContinuing pull on lanyard 100 moves radius 86 on sear 74 into contactwith rear wall 51 and the axis of movement .t.r of the sear becomesangularly positioned relative to the rear wall so that as the sear movesaccelerating member .38 rearwardly it is simultaneously cammed inwardlyto its release position. Also, while accelerating member .38 isdisplaced rearwardly so that bottom wall li9 draws away from end 66striking member 40 follows, under the bias of spring 54.

When sear 74 is entirely disengaged from rear wall 51, acceleratingmember 38 is free to be impelled forwardly by energized spring 42 to itsforward position. Striking member 40 is propelled forwardly byaccelerating member .38 and when the accelerating member is stopped inits forward position by contact of the front end thereof with shoulder24 of bore 16, striking member 40 continues on under its inertia to itsstriking position to fire the chambered cartridge. Immediately uponstriking member 40 being stopped in its striking position the tension cfthe compressed spring 54 returns it to its retracted position relativeto accelerating member 38 whereby pin 58 is retracted within breechblock14 and so cannot be damaged when the breechblock is opened forchambering another round.

When accelerating member 38 was released by sear 74, and was impelledforwardly, the sear was held in its release position by contact ofextending end 84 thereof with circumferential area 50. After cannon 12is fired and lanyard 100 is released, actuating device 70 is rotatedback to its normal position by spring 106 and when sear 74 comes intoregistry with channel 48 it automatically snaps thereinto so that firingmechanism 20 is ready to fire another round.

From the foregoing it is readily apparent that there is provided hereinfor cannons a manually actuated firing mechanism which is simple indesign and positive in operation, which requires a minimum of machiningin the breechblock for installation therein, is easily adjustable torovide direct pull on the lanyard for all quadrant elevations of thecannon and which provides a minimum of displacement of the lanyard forcocking and releasing the tiring pin.

Although a particular embodiment of the invention has been described indetail herein, it is evident that many variations may be devised withinthe spirit and scope thereof and the following claims are intended toinclude such variations.

ll claim:

l. in a cannon having a breechblock, a firing mechanism including atiring pin assembly, an accelerating member cf said tiring pin assemblydisposed for longitudinal displacement in the breechblock between aretracted and a forward position, means for biasing said acceleratingmember to the forward position, an actuating device provided with ashaft transversely mounted in the breechblock for rotationaldisplacement therein, a sear mounted in said shaft for translationaldisplacement therein between an engaging and a release position along adesign axis of movement and for angular displacement with said shaftbetween a normal and a disengaged position, an extending end of saidsear, a spring for biasing said sear to the engaging position, springmeans operationally disposed between the breechblock and said shaft toproduce a torque for biasing said shaft in a direction to displace saidsear angularly to the normal position, an annular channel formed in saidaccelerating member for receiving said extending end of said sear whenin the normal position, a rear wall formed by said channel and arrangedfor contact by said extending end of said sear during angulardisplacement thereof from the normal position to actuate saidaccelerating member to the retracted position, a radius formed on saidextending end of said sear and disposed for camming contact with saidwall during displacement of said sear to the disengaged position, saidshaft being so positioned in the breechblock respective to said rearwall that rotation of said sear by said shaft from the normal positionfor actuating said accelerating member to the retracted positionincreases the angular relationship of the design axis of movement ofsaid sear to said rear wall so as to transmit a part of the forceapplied by said sear to said rear wall back to said sear fortranslational actuation thereof against the bias of said spring to thedisengaged position.

2. The invention as defined in claim 1 wherein said shaft includes asection extending outside the breechblock, said actuating deviceincludes a rod extending through the extending section of said shaft, aring mounted for angular and axial displacement on the extending end ofsaid shaft a plurality of angularly related grooves formed in theoutside of said ring so as to be selectively alignable with extendingends of said rod when said ring is rotated for adjusting the angularposition thereof on said shaft, and an ear extending from thecircumference of said ring for connecting a lanyard thereto, and whereinsaid spring means operationally disposed between the breechblock andsaid shaft is of torsion-compression type and is mounted one theextending section of said shaft between the breechblock and said ringand anchored at opposite ends thereto for simultaneously biasing saidring away from the breechblock to engage the selected ones of saidgrooves with said rod and thereby connect said ring with said shaft atthe adjusted position and bias said shaft angularly to return said searto the normal position.

References Cited UNITED STATES PATENTS 687,332 11/1901 Noble 89272,503,309 4/1950 Weiss 8927 2,504,162 4/1950 Summerbell et a1 8927FOREIGN PATENTS 4,839 1894 Great Britain.

BENJAMIN A. BORCHELT, Primary Examiner.

S. C. BENTLEY, Assistant Examiner.

